Alert archive / Alabama / Mesoscale Discussions in 2021
Mesoscale Discussion 217
The Storm Prediction Center issued this mesoscale discussion at Mar 17, 2021, 10:15 PM CDT for 24 counties in Alabama; Escambia County, Okaloosa County, Santa Rosa County, Florida; Quitman County, Georgia. It was in force for 90 min.
The area
The outline as issued.
The facts
- Issued
- Mar 17, 2021, 10:15 PM CDT (03:15 UTC)
- Expired
- Mar 17, 2021, 11:45 PM CDT
- In force
- 90 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 36
All 28 counties
Baldwin County, AL, Barbour County, AL, Bullock County, AL, Calhoun County, AL, Chambers County, AL, Cherokee County, AL, Clay County, AL, Cleburne County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Elmore County, AL, Escambia County, AL, Geneva County, AL, Lee County, AL, Macon County, AL, Mobile County, AL, Montgomery County, AL, Pike County, AL, Randolph County, AL, Russell County, AL, Tallapoosa County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, Quitman County, GA
The radar
The Maxwell AFB radar (KMXX), 81 km from the middle of the area, began a volume at 03:18 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Birmingham, AL (KBMX), launched 00:00Z, 3.3 hours before the alert went out and 128 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 188 J/kg
- Mixed-layer CIN
- -25 J/kg
- Mixed-layer LCL
- 669 m above ground
- 0-6 km bulk shear
- 63 kt
- 0-1 km storm-relative helicity
- 336 m²/s²
- 0-3 km storm-relative helicity
- 465 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.6
The text
As transmitted.
521
ACUS11 KWNS 180316
SWOMCD
SPC MCD 180315
GAZ000-ALZ000-FLZ000-MSZ000-180445-
Mesoscale Discussion 0217
NWS Storm Prediction Center Norman OK
1015 PM CDT Wed Mar 17 2021
Areas affected...AL and the panhandle of Florida
Concerning...Tornado Watch 36...
Valid 180315Z - 180445Z
The severe weather threat for Tornado Watch 36 continues.
SUMMARY...Although the overall severe weather threat has waned,
potential for storms capable of producing damaging wind gusts and/or
tornadoes continues. This still includes at least some risk for an
isolated strong tornado or two, mainly across parts of southeastern
Alabama and perhaps adjacent portions of southwestern Georgia and
the panhandle of Florida.
DISCUSSION...Recent, lingering supercell development to the
northwest of Montgomery has diminished, likely due to the waning
boundary-layer instability, just ahead of an east-northeastward
surging segment of a more extensive eastward advancing pre-frontal
squall line. This segment appears on track to reach the
Alabama/Georgia state border vicinity, near/northwest of Columbus GA
by around 05Z. As it does, inflow of moist boundary-layer air to
areas farther north probably will become cut off, as cooler/drier
boundary layer air remains entrenched across and north of the
Georgia piedmont.
Largely due to the strength of the lower/mid tropospheric wind
fields and shear, the environment could still become marginally
conducive to the risk for severe wind gusts and/or a tornado or two
along/just ahead of the squall line across northeastern and east
central Alabama through 04-05Z. However, into the overnight hours,
the primary severe weather potential may increasingly become focused
across parts of the panhandle of Florida into southeastern Alabama
and adjacent southwestern Georgia.
Even this may still be somewhat sporadic/localized, as the southern
fringe of the stronger mid/upper support shifts into the southern
Appalachians. However, 40-50+ kt south-southwesterly 850 mb flow
overspreading this region will contribute to sizable clockwise-
curved low-level hodographs in the presence of moist and weak to
unstable boundary layer air. This could promote supercell
structures with the potential to produce a strong tornado or two.
..Kerr.. 03/18/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FFC...TAE...BMX...MOB...LIX...
LAT...LON 33018620 34478550 31988481 30668613 30278872 31228769
31888628 33018620SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 17, 7:07 PM CDT | Tornado Watch | SPC | Colbert, Cullman, Franklin, Lauderdale, Lawrence, Limestone and 3 more | 3 hr |
| Mar 17, 9:16 PM CDT | Mesoscale Discussion | SPC | Cullman, DeKalb, Jackson, Limestone, Madison, Marshall and 1 more | 89 min |
| Mar 17, 11:02 PM CDT | Tornado Watch | SPC | Coffee, Covington, Dale, Geneva, Henry, Houston | 9 hr |
| Mar 18, 1:52 AM CDT | Mesoscale Discussion | SPC | Barbour, Coffee, Covington, Dale, Geneva, Henry and 2 more | 83 min |
| Mar 18, 4:28 AM CDT | Mesoscale Discussion | SPC | Coffee, Dale, Geneva, Henry, Houston | 92 min |
| Mar 18, 6:32 AM CDT | Mesoscale Discussion | SPC | Bay, Calhoun, Franklin, Gadsden, Gulf, Jackson and 6 more | 58 min |
| Mar 18, 6:53 AM CDT | Tornado Watch | SPC | Dixie, Franklin, Gadsden, Gulf, Jefferson, Lafayette and 5 more | 5 hr |
| Mar 18, 10:05 AM CDT | Mesoscale Discussion | SPC | Columbia, Dixie, Hamilton, Jefferson, Lafayette, Madison and 2 more | 115 min |
| Mar 18, 10:42 AM CDT | Tornado Watch | SPC | Alachua, Baker, Bradford, Clay, Columbia, Duval and 7 more | 6 hr |
| Mar 18, 9:34 AM CDT | Mesoscale Discussion | SPC | Banks, Barrow, Clarke, Elbert, Franklin, Habersham and 5 more | 2 hr |
| Mar 18, 1:08 PM CDT | Tornado Watch | SPC | Elbert, Lincoln | 4 hr |
| Mar 18, 2:10 PM CDT | Mesoscale Discussion | SPC | Elbert | 3 hr |
Nearby
Mesoscale Discussions in Alabama, 2021Mesoscale Discussions in Florida, 2021Mesoscale Discussions in Georgia, 2021Every mesoscale discussion in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.